This invention relates generally to wellhead equipment, including a so-called xe2x80x9chorizontal treexe2x80x9d, for use in the drilling and completion of a subsea well.
As compared with a conventional Christmas tree, a horizontal tree includes a spool connected to the upper end of the wellhead housing and having a bore in which a tubing hanger may be landed for suspending a tubing string within the well. The spool has ports with valves to control the flow of hydrocarbons through the tubing and tubing/casing annulus, as well as to permit workover of the well, as in conventional equipment, despite plugs removable installed in its bore above the hanger. Upon removal of the plug, the tubing hanger may be removed through a blowout preventer (BOP) mounted above the spool, without requiring removal of the tree, thus providing a significant advantage for wells where there is a risk of having to pull the tubing.
In wellhead equipment of this type, hydraulic control fluid is supplied from a remote source to a downhole function, such as the fluid responsive operator for a subsurface safety valve (SSSV) which is carried by the tubing string to normally maintain the tubing open but close it in response to emergency conditions by reduction of the hydraulic fluid pressure on the operator. In such equipment, hydraulic fluid is adapted to be supplied to the operator from a source at the surface through fluid passageways in the spool and hanger whose sealing surfaces are adapted to be aligned and sealed with respect to one another to fluidly connect them when the hanger is oriented into a landed position in the spool bore. This type of equipment has become known in the art as a xe2x80x9cpenetratorxe2x80x9d, presumably by virtue of the ability to penetrate the tubing hanger leading to the SSSV. See, for example, U.S. Pat. Nos. 5,465,794, 5,555,935, 5,865,250, 6,119,773, 6,244,348 B1 to ABB Vetco.
In at least one of these patents, the fluid passageway in the hanger includes an insert installed in an opening in the hanger connecting with its bore and having a normally closed poppet valve which may be opened to permit the hydraulic fluid to be supplied through an adaptor to the SSSV operator, in order to open the tubing. The poppet valve is then permitted to close as the SSSV is maintained open. Pressure fluid is exhausted from the operator to permit the valve to close in the event of an emergency.
More particularly, the inner end of a stem on which the poppet valve is mounted protrudes from the seal surface of the fluid passageway in the hanger to engage the seal surface of the spool, and thus be moved to open position, as the hanger is lowered into landed position. This permits fluid from the remote source to urge the operator of the SSSV to open position.
In the case of penetrators made pursuant to such patents, the sealing surface about the opening in the spool or the sealing is formed on a spherical surface in the bore of the spool, which is understandably difficult to form and refinish in the event of damage.
In the penetrator shown in U.S. Pat. No. 5,582,438, to Kvaerner Oil Field Products, and other patents based thereon, the fluid passageway in the hanger is formed on the end of a tubular body received in a carrier which is initially spaced from the spool bore, as the hanger is lowered into the spool bore, and then cammed inwardly to cause a seal surface on its end to engage a seal surface within the bore of the spool. Among other things, the mechanism by which the body is moved to sealing position requires a large number of moving parts.
In each of these prior penetrators, the hanger and spool are provided with parts for orienting their seal surfaces into axially aligned position. However, there is the possibility that the seal surfaces on the hanger and spool may not be sufficiently axially misaligned, when landed, as to prevent leakage between the hanger and spool.
It is the primary object of this invention to provide a penetrator of this type which, in its preferred and illustrated embodiment, overcomes one or more, and preferably all, of these problems and further which has other distinct advantages over the prior art penetrators.
In accordance with the illustrated and preferred embodiment of the present invention, the tubular body of the insert in the fluid passageway of the hanger has a spherical surface at one end, and a seat ring releasably held on the inner end of the body mounted on the inner end of the body has a matching sealing surface for swiveling within the spherical surface in the insert, as ports through the insert and seat ring are maintained in fluid communication. A seal ring surrounds one end of the port in the seal surface, and another seal ring surrounds the other end of the port in the spherical end of the seat ring for sealing with respect to the spherically shaped end of the insert body to maintain a seal between the surfaces despite minor axially alignment.
In accordance with another novel aspect of the invention, the axes of the fluid passageways in the spool and hanger extend at an acute angle with respect to one another, and the flat seal surfaces on them are disposed within parallel planes which extend at vertical angles perpendicular to the axes of the passageways. More particularly, one of the seal surfaces is resiliently urged to a position in which it is engaged by and then cammed inwardly by the other seal surface as the hanger is lowered therepast.
In the illustrated and preferred embodiment of the invention, the seal surface on the end of the fluid passageway of the spool comprises a bellows which extends within the spool opening and has its outer end carried by a flange releasably attached to the outer side of the spool. Thus, the bellows is removable from the spool opening for replacement or repair of its sealing surface on its inner end upon disconnection of the flange from the outer side of the hanger.
As illustrated and described, the seal surface of the bellows has a seal surface which extends from the spool opening into a position to be engaged by and cammed outwardly by the seal surface of the hanger. More particularly, the spool opening has an inwardly facing shoulder, and the bellows has an outwardly facing shoulder to position the seal surface to be engaged and cammed outwardly as the seal surface on the hanger slides downwardly over the seal surface on the bellows.